The invention relates to a colour display tube comprising an envelope having a substantially rectangular display window provided with an upright edge and a substantially rectangular colour selection electrode having a large number of apertures. The colour selection electrode is suspended in the corners of the display window with the aid of suspension means comprising flat resilient elements connected to the colour selection electrode. Each flat resilient element is substantially perpendicular to the electron beams deflected towards the respective corner of the display window.
Such a colour display tube is disclosed in U.S. Pat. No. 3,986,071. In this tube, two metal pins are sealed in each corner of the upright edge of the display window, which pins extend in a direction perpendicular to the tube axis. Clamping springs are connected to the ends of the flat resilient elements remote from the colour selection electrode. The clamping springs have two notches. The colour selection electrode is suspended in the display window by sliding the clamping springs with the notches over the pins, the notches engaging the pins. In order to prevent the clamping springs from sliding along the pins during shocks or vibrations of the tube, a large clamping pressure of the clamping springs is required. As a result of this large clamping pressure, which is transferred to the glass by the pins, stresses occur in the glass. This increases the possibility of fracture in the usual temperature treatments to which the display tubes are subjected during manufacture. Moreover, in such a tube poor positioning reproducibility is obtained when the colour selection electrode is repeatedly mounted in and removed from the display window, because the clamping springs do not always assume the same position on the pins. Positioning reproducibility is to be understood to mean herein the extent to which the colour selection electrode assumes the same position during repeated removal and mounting which is necessary during the photographic provision of the display screen on the display window.